Do I remember correctly that you shoot with a DP of some sort? How would you compare the operational slowness to the PEN you use. I think those first 2 PENS were fast enough for most shooting situations I used them in, but I occasionally hear those referred to as slow as well. I wonder if it's just people comparing apples to oranges.
You do remember correctly, I have a DP2s ... and I think it's definitely a case of Malus
vs Citrus ... but I'm also not really sure what "operational speed" is. Does it mean fast to start, small shutter lag, fast autofocus, ease of menus ... the trouble is these things carry different weight for different people. I find I can change ISO, aperture, shutter speed as quickly or quicker with the DP2s as with the E-P2. The thing that is noticeably slow about it is the autofocus in less than good light or on low-contrast scenes. This occasionally annoys me, but only occasionally. I can't think of a single occasion when some aspect of the E-P2 was so "slow" that I either got annoyed or missed a picture, by the way.
So ... one either works within a camera's limitations or one buys something one likes better. This is true of any camera (or knife, car, guitar, television, trousers ... ).
I work within very severe limitations in my E-P2's dynamic range, which means rarely shooting above ISO200. It doesn't make me a fool for using it, or make the E-P2 a bad camera, and nor do the limitations of the DP series. The cameras I use makes no impact on how good or bad or indifferent my pictures look.
Sigma don't market it as a P&S to suit all situations (or say that it's fast), so it's not as though anyone gets taken in by ridiculous claims that can't be supported. If you buy one and expect to shoot small children at speed or ice hockey you'll be sorely disappointed. But you also wouldn't have done your homework before putting own your cash.